Model car racing system

ABSTRACT

A mode car racing system wherein the driver can steer the model car at such times as he so elects, said model car being constrained to follow the course of the track at all other times, and in a preferred embodiment comprising a track having a multiplicity of parallel slots following the course of the track, electrical terminals interspersed on the track and supplying speed and steering control voltages to the model cars regardless of the displacement of a model car along or across the track, key means depending from the model car and engaging the slots of the track, said key means displacing itself and the attached model car to adjacent slots and thereby across the width of the track in response to the steering control voltage.

United States Patent 4 Claims, 7 Drawing Figs.

3.239 963 3/1966 Smith et al. 273/86 X 3,339.307 9/1967 Floyd et al. 273/86 X 3,373,524 3/1968 Nirenberg 273/86 X Primary Examiner-Anton O. Oechsle ABSTRACT: A mode car racing system wherein thedriver can steer the model car at such times as he so elects, said model car being constrained to follow the course of the track 1 Cl 273/86 at all other times, and in a preferred embodiment comprising a 180/2, 8 track having a multiplicity of parallel slots following the [5 I] Int. Cl A63h 29/22, course of the track, electrical terminals interspersed on the 1A63f9/14 track and supplying speed and steering control voltages to the {50] F'eld Search model cars regardless of the displacement of a model car ISO/3791146344 along or across the track, key means depending from the model car and engaging the slots of the track, said key means [56] References Cned displacing itself and the attached model car to adjacent slots UNITED STATES PATENTS and thereby across the width of the track in response to the 2,537,281 l/l95l Roshak 273/86 steering control voltage.

we; 24 701%}14 era "g3 74 r ,44 i S I so PATENTED 22 lsn SHEET 2 BF 4 MODEL CAR RACING SYSTEM This invention relates to model car racing systems and more particularly concerns a method which enables a driver to steer a model car as well as to control its speed.

The term driver" as used herein denotes a person who remotely controls a model car.

The term steering" as used herein denotes the capability of a driver to remotely produce a continuous lateral displacement of a model car across the width of a model track, said displacement being at right angles to the forward motion of the model car along the length of the track.

In prior model car racing systems-so called slot car racing-each model car is constrained to follow a particular circumferential slot in the surface of the model track without any control of the steering of the model car by the driver. The driver controls only the speed of the model car by varying the electrical power supplied to it through metallic terminals on both sides of the slot. This arrangement relieves the driver of the burdensome and difficult task of continually steering the model car. Steering a model car around a model race track is difficult because the model car rounds turns in a very short time compared to a real automobile race. Very few persons would have the skill or endurance to continually steer the model car.

The confinement of each model car to a particular slot in the track in the prior art makes it a simple matter to supply electromotive power separately to each model car through continuous, elongated terminal strips adjacent to each slot. The capability of supplying electromotive power externally, as compared to obtaining power from batteries carried by the model car itself, is important. There are many objections to using batteries such as their size and weight, loss of power with use, and the difficulty that the batteries of each car in the race may not be in equally good condition and thereby placing some cars at an unfair disadvantage.

Notwithstanding its many excellent features, conventional slot car racing has one serious deficiency. This deficiency is that the absence of a capability for steering the model car makes such racing a less-than-acceptable simulation of a real automobile race. Model car racing would be more enjoyable if the driver could steer the model car as well as control its speed. Yet, the driver should not be burdened with having to steer the model car at all times. It would be desirable if there were a method whereby the driver could steer the model car when he so chooses, but which would not require him to steer the model car at all times.

It is an object of the present invention to provide the driver of a model car with a capability for steering the model car at such times as he so chooses, said model car being constrained to follow the course of the model track when it is not being steered.

lt is another object of the present invention to provide means for supplying external electrical power to a model car to control its speed and steering regardless of the location on the model track to which the model car has been steered.

The more skillful the driver, the more he may choose to steer the model car. Skillful steering will help the driver to win the race. For example, it will enable him to pass other model cars and obtain the preferred position on the inside of the track. Yet, the driver is not burdened by being required to steer the model car continually. An unskilled driver may choose to do little steering. As his skill increases with practice, the driver may choose to steer more often.

In accordance with the present invention, the model track is provided with a multiplicity of adjacent, parallel paths following the course of the track. In an exemplary form of the present invention, said parallel paths take the form of parallel, circumferential slots in the surface of the track. The spacing between slots is much smaller than the width ofthe wheels ofa model car so that said wheels ride on the upper surface of the track. Electrical terminals interspersed over the surface of the track and in each slot provide electrical connections to the driver's speed and steering control unit, or controller, regardless of the particular slot a model car is following. A model car is constrained to follow the slot on which it happens to be until it is steered to an adjacent slot by the driver. Thus, when a model car is not being steered by the driver, it will automatically follow the course of the track. Steering is accomplished by steering means within a model car responsive to electrical signals transmitted to the model car through the interspersed terminals on the track, said steering means engaging a slot of the track and causing a continuous, sidewards displacement of the model car to adjacent slots until the steering action is terminated by the driver. While such sidewards displacement of the model car is somewhat different than the steering accomplished by turning the front wheels ofa real automobile, it is sufficiently similar as far as the end result is concerned in that the model car is caused to move continuously from one side of the track ro the other under the control of the driver. There are two separate sets of interspersed electrical terminals in the slots of the track, one of said sets for each of two model cars in the race. When a model car is placed on the track so that it contacts one set of terminals, it cannot contact the other set of terminals even when it is steered from side to side, thereby allowing each driver to control only his own model car. When there are to be more than two model cars in the race, additional sets of interspersed terminals are provided.

An alternative form of the present invention, particularly useful when many model cars are to be raced, employs the same set of track terminals for all model cars, but utilizes multiplexed electrical signals on the common track terminals to effect separate control of each model car. An exemplary form of the invention utilizes frequency multiplexing. Narrow band, frequency selective, electronic amplifiers in each model car select the proper control signals for that car. The electronic amplifiers in the model cars are powered by a direct-current voltage applied to the common track terminals.

Other objects and various additional features and advantages of the invention will become apparent from the following detailed description of illustrative embodiments thereof taken in conjunction with the attached drawings and the appended claims.

In the drawings:

FIG. 1 is a plan view of the model race track showing the configuration of the parallel slots in the surface of the track.

FIG. 2 is a front view of a model car on the model track showing the details of the steering mechanism and the method of supplying electrical power from an external source to the model car through interspersed terminals on the track.

FIG. 3 shows the cross section of the model track and the means by which electrical power is returned from the model car to the external source.

FIG. 4 is a schematic diagram showing the interconnection of the driver's speed and steering controller, the track terminals, the brushes of the model car, and the speed and steering control motors of the model car.

FIG. 5 shows a cross section of the track in a modified form of the invention wherein a single set of track terminals carrying multiplexed control signals is used by any number of model cars.

FIG. 6 is a schematic diagram of the electronic unit in each model car required to separate the multiplexed control signals in the modified form of the invention.

FIG. 7 is an enlargement of the portion of the model track inside circle 9 of HG. l.

Referring to FIG. 1, a model track 12 of the present invention is shown in plan view. The track has the form of a closed loop of oval shape. In the surface 14 of the track are many equally spaced, parallel slots 16 following the course of the track. When not being steered by the driver, the model car is constrained to follow a particular slot of the track. When the driver actuates the steering mechanism, as described below, the model car moves continuously to successive, adjacent slots, to the left or right as selected by the driver, until the driver terminates the steering action.

Referring to FIG. 2, a model car 18 of the present invention is shown in front view riding on the model track 12. The cross section of the track shown in FIG. 2 is along the line 7-7 of FIG. I. The wheels 20 of the model car are much wider than the slots 16 in the track so that the model car rides upon the upper surface 14 of the track. Key means 22 depends from the underside 24 of the model car, engaging slots 26, 28, of the track and constraining the model car to move along the track on a particular path. Key means 22 comprises a timing belt 32 in the form of a loop with interior teeth 34, end gears 36, 38 which engage and drive the timing belt, center gear 40 which engages and drives the outer gears, and guide teeth comprising active teeth 42 and dummy teeth 44 attached to the exterior of the timing belt in alternating fashion and meshing with the slots 16 of the track. The support for key means 22 comprises support rods 58, 62 connected at their lower ends to the axle housings 52, 56 of the end gears 36, 38 and connected to the underside 24 of the model car through compression springs 64, 68 in sleeves 70, 74.

Attached to the bottom of every other slot are pairs of elongated, metallic track terminals 76, 78, each pair comprising an A terminal and a B terminal. Attached to the bottom of the remaining slots are other pairs of elongated, metallic track terminals 80, 82, each of said other pairs comprising an A terminal and a B terminal. All track terminals having the same letter designation, such as A, are connected together. Track terminals A and B supply the electrical power for controlling the speed and steering, respectively, of a first model car in the race. Track terminals A and B supply the electrical power for controlling the speed and steering, respectively, of a second model car in the race. The elongated track terminals are shown in FIG. 7, which is a plan view of an enlarged portion of the model track included within the circle 9 of FIG. I. As shown in FIG. 4, the track terminals are connected to the controller 83 used by the driver to control the speed and steering of the model car.

Each active tooth 42 has a pair of metallic pickup brushes 84, 86, denoted left and right, respectively, separated from one another by an insulator 88 In FIG. 2 the active teeth are shown in the slots containing track terminals A and B. Compression springs 64, 68 press said pickup brushes against said track terminals, forming a sliding electrical connection. The dimensions of the guide teeth 42 are chosen sothat the left pickup brush 84 can contact only terminal A, while the right pickup brush 86 can contact only terminal B. Wires 90 and 92 connect left and right pickup brushes 84 and 86, respectively, to motors 94 and 96, respectively, within the model car, said motors controlling the model cars speed and steering, respectively, as indicated schematically in FIG. 4. The dummy teeth 42 perform no electrical function but provide more complete meshing of the key 22 with the track 12 than would occur if only the active teeth meshed with the track.

The method of completing the return circuit from the speed and steering control motors to the drivers controller 83 is indicated in FIG. 3, which shows a cross section of the track along the line 7-7 of FIG. I. The return terminals 98 are elongated, metallic strips located on the top surface 14 of the track 12, with one return terminal between every slot of the track. The return terminals are denoted C in FIG. 3 and in the schematic diagram of FIG. 4. The model car makes contact with the return terminal 98 by means of a metallic return brush 100 depending from the underside 24 of the model car and held firmly against the track. The return brush is much wider than the spacing between slots in the track so that it rides on the upper surface of the return terminals. The return brush is pressed against the return terminals by compression springs 101, 103 attached to the underside 24 of the model car and enclosed in cylindrical sleeves 105, 107, also attached to the underside of the model car. A wire 91 connects the return brush to the speed control motor 94 and steering control motor 96.

FIG. 4 is a schematic diagram showing the electrical connections from the driverscontroller to the track terminals, from there to the speed and steering control motors within the model car, from there to the return terminal, and then back to the controller. Within the controller 83, power supply I06 furnishes fixed voltages to speed control rheostat I02 and steering control rheostat I04. Speed control rheostat 102 supplies a variable control voltage through track terminal A 76 to left pickup brush 84, which is connected by a wire 90 to the speed control motor 94. Steering control rheostat 104 supplies a variable control voltage through track terminal B 78 to right pickup brush 86, which is connected by a wire 92 to the steering control motor 96. The return circuit from speed control motor 94 and steering control motor 96 is through a common wire 91 to the return brush 100, and from there through the return terminal C 98 to the power supply 106.

In operation, one of the two model cars in the race is placed on the track so that the active teeth 42 of its key 22 engage slots containing track terminals A 76 and B 78, while the second model car is placed on the track so that its active teeth engage slots containing track terminals A and B 82. Referring to the first model car, its active teeth contact track terminals A and B and receive speed and steering control voltages, respectively, through said track terminals. The speed control voltage is applied to the speed control motor 94, which drives the wheels of the model car. The steering control voltage is applied to the steering control motor 96, which turns the center gear 40 of key means 22. Center gear 40 drives the end gears 36, 38 in the same direction, causing the timing belt 32 to rotate. The rotation of the timing belt causes the active and dummy teeth at one end of the key to lift away from the track while the active and dummy teeth at the other end of the key mesh with the track, with the result that the key and the model car attached to it are displaced sidewards across the track at right angles to the forward motion of the model car. The steering control motor is a reversible DC motor. The polarity and magnitude of the DC voltage supplied to the steering control motor determine, respectively, the direction in which the model car is steered and the rate at which it is steered. The speed control motor is also a reversible DC motor, allowing the model car to be accelerated or braked in accordance with the polarity of the DC speed control voltage. The speed and steering of the second model car in the race is controlled in the same manner as described above through track terminals A and B.

A modification of the present invention is shown in FIG. 5. This modification provides an alternative to the use of separate sets of track terminals for the two model cars in the race and for the steering and speed control functions. The modification allows any number of model cars to he raced at the same time by multiplexing speed and steering control signals onto a single set of track terminals. The preferred method of multiplexing is to frequency multiplex the control signals, by modulation onto separate subcarriers, to distinguish between speed and steering commands and between the model cars. Electrical power and the frequency multiplexed control signals are supplied through the single set of track terminals D 108 used by all the model cars. The return terminal C 98 is on the upper surface of the track as before. All guide teeth 109 are now active teeth and each has a single metallic brush 1 11 which makes contact with the track terminals 108.

Referring to FIG. 6, a DC supply voltage denoted B and low level speed and steering control signals modulated on subcarrier frequencies f,, F f f,, are applied between the common track terminal D 108 and the return terminal C 98. Two narrow-band, tuned, transistorized, electronic amplifiers I10, 112 in each model car select the correct speed and steering control signals for that car. Thus, f and f control the speed and steering, respectively, of the first model car, f and f control the speed and steering, respectively, of the second model car, and so on. Considering the first model car, the supplied DC, or 8*, voltage 114 provides the DC potentials required to operate the transistorized amplifiers I10, 112 and other electronic units in the model car. Blocking capacitors 116, 118 at the inputs to the tuned amplifiers 110 112 keep the B voltage out of the tuned amplifier inputs, while a choke 120 in the 8* line keeps the subcarrier frequencies out of the B supply voltage. After passing through the tuned amplifiers 110, 112, the subcarrier signals are demodulated by demodulators 122, M4 and the demodulated control signals are amplified in power amplifiers 126, 128. The amplified speed and 2control signals are applied to the speed and steering control motors 94, 96, respectively. Amplitude modulation of the subcarriers is preferred because of the simplicity of the modulator, which is merely a variable attenuator controlling the magnitude of the subcarrier, and because of the simplicity of the demodulator, which is merely an envelope detector and low-pass filter. However, any other form of modulation, such as frequency modulation, may be used, in conjunction with the appropriate demodulation means. The model cars in the race are identically constructed, except that one model car accepts frequenciesf andf a second model car accepts frequenciesf, andf and so on. The advantage of using multiplexed signals, rather than separate sets of track terminals, for controlling speed and steering is that any number of model cars may participate in the race using the same set of track terminals.

It is to be understood that the present invention, while described in the context of a race between model cars, is meant to be generally applicable to any use of model cars, or other model vehicles,. wherein it is desired to control both their speed and steering. For example, the principles of the invention may be used to control the passage of one or more model cars through an obstacle course, where it is necessary to steer the model cars to avoid obstacles on the model course, or track.

It is to be understood that the key means of the present invention is not limited to the timing belt embodiment described herein but may employ instead any other suitable drive means, a worm gear meshing with the slots of the track for example, which allows the track terminals to be contacted at all times while the key moves the model car across the width of the track.

it is to be understood that the particular embodiment of my invention described above and shown in the drawings is merely illustrative of and not restrictive on the broad invention, and that various changes in design, structure and arrangement may be made without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. ln a model car racing system, the combination of at least one model car, a model track having a multiplicity of adjacent parallel paths following the course of the track, said parallel paths consisting of parallel slots in the surface of the track, electrical terminals on the track interspersed among said parallel paths for the purpose of supplying voltages to said model car to control its speed and steering independent of one another and independently from one model car to another regardless of the displacement of said model car along or across the track, said interspersed electrical terminals comprising separate sets of terminals, each model car including means responsive to separate control voltages to independently vary the speed and steering thereof, each model car including means for receiving control voltages from a single set of said terminals, said receiving means including metallic brushes depending from said model car and making electrical contact with the electrical terminals on the track for the purpose of receiving said control voltages, key means depending from each model car and engaging at least one slot of the track for the purpose of guiding each model car around the track on any of said parallel paths and for the purpose of locating each model car in a definite position relative to the interspersed electrical terminals in order that said depending metallic brushes may contact the appropriate electrical terminals, control means for supplying control voltages to each model car independently through said interspersed electrical terminals for the purpose of adjusting the speed and steering of each model car, first electromotive means in said model car responsive to said speed control voltage and supplying a driving torque to the wheels of said model car for propelling said model car along the track at the desired speed, second electromotive means in said model car responsive to said steering control voltage and supplying a force for displacing said key means and the attached model car to an adjacent path of the track in a direction and at a rate determined by the steering control voltage, whereby each model car may be individually controlled by its own driver, and whereby said model car may be steered to any position across the width of the track by the actuation of the steering control voltage at any time the driver so desires, said model car at all other times being guided along the course of the track in the path to which it had last been steered, and whereby said model car may be controlled as to speed independent of the position across the track to which it has been steered.

2. In the model car racing system defined in claim 1, wherein said terminals include a speed control terminal and a steering control terminal in each slot having the form of continuous metallic strips on the bottom of and following the en tire length of said slots, a common return terminal for the speed and steering control voltages in the form of continuous metallic strips on the surface of the track in between and following the entire length of said slots, said terminals of like function in alternate slots being connected together to form separate sets of terminals, each separate set of terminals supplying control voltages to a different model car, said key means comprising a timing belt rotated from its interior by gears driven by a motor responsive to the steering control voltage and guide teeth on the exterior of the timing belt, said guide teeth having the same spacing as the slots of the track and meshing with the slots of the track when the model car is set down on the track, said guide teeth consisting alternately of electrically active teeth and electrically inactive, or dummy, teeth, said dummy teeth providing more complete meshing of said key with the track, said active teeth including said metallic brushes, said brushes being in the form of first and second metallic pickup brushes at the extremity of each said active tooth for the purpose of contacting the speed and steering control terminals, respectively, in the bottom of a slot, said first pickup brush being connected to and supplying power to the speed control motor in said model car and said second pickup brush being connected to and supplying power to the steering control motor in said model car, said key means being held firmly against the track by spring tension, a metallic return brush depending from said model car and held firmly against the upper surface of the track by spring tension and making electrical contact with the common return terminals, said return brush providing the common return circuit for the speed and steering control voltages applied to the speed and steering control motors, respectively, a speed and steering controller for each model car comprising a power supply and a first and second rheostat, said rheostats controlling the magnitude and polarity of the voltage supplied to the speed and steering control motors, respectively, whereby a model car which is on the track with its key means engaging the slots of the track can receive speed and steering control voltages through only one of the separate sets of track terminals, and whereby when the steering control voltage is supplied to said model car said timing belt turns, moving said key means and the attached model car sidewards across the track under the control of the driver until the steering action is terminated by the driver, and whereby when no steering control voltage is supplied said model car continues .to be guided around the track by said key means engaged in the slots of the track to which it had last been steered.

3. ln a model car racing system, the combination of at least one model car, a model track having a multiplicity of adjacent parallel paths following the course of the track, said parallel paths consisting of parallel slots in the surface of the track, electrical terminals on the track along said parallel paths, said electrical terminals being used in common by each model car,

said electrical terminals providing a direct-current supply voltage and control voltages to said model cars to control their speed and steering independent of one another and independently from one model car to another regardless of the displacement of said model car along or across the track, said control voltages comprising pairs of multiplexed electrical signals, each model car including first and second electronic means responsive to a particular pair of said multiplexed signals to independently vary the speed and steering thereof, each model car including means for receiving said control voltages from said electrical terminals, said receiving means including metallic brushes depending from said model car and making contact with the electrical terminals on the track, key means depending from each model car and engaging at least one slot of the track for the purpose of guiding each model car around the track on any of said parallel paths and for the purpose of locating each model car in a definite position relative to said electrical terminals in order that said depending brushes may contact said electrical terminals, power supply means providing a direct-current supply voltage to said electrical terminals, a controller for each model car to provide said control voltage, the controller for a particular model car being actuated by the driver of said particular model car, said first and second electronic means within each model car being powered by said direct-current supply voltage, said first electronic means responsive to one of said pair of multiplexed signals and said second electronic means responsive to the other of said pair of multiplexed signals, said first and second electronic means each comprising demultiplexing means, demodulating means and amplifying means, first electromotive means in said model car responsive to the output of said first electronic means and supplying a driving torque to the wheels of said model car for propelling said model car along the track at the desired speed, second electromotive means in said model car responsive to the output of said second electronic means and supplying a force for displacing said key means and the attached model car to an adjacent path of the track, whereby each model car may be individually controlled by its own driver, and whereby each model car may be steered to any position across the width of the track at any time the driver so desires, said model car at all other times being guided along the course of the track in thepath to which it had been last steered, and whereby said model car may be controlled as to speed independent of the position across the track to which it has been steered.

4. In the model car racing system defined in claim 3, wherein said electrical terminals include common track terminals comprising a single continuous metallic strip on the bottom of and following the length of each slot, said metallic strips in the various slots being connected together electrically, a common return terminal for the electrical signals supplied on said common track terminals in the form of continuous metallic strips on the surface of the track in between and following the entire length of said slots, said key means comprising a timing belt rotated from its interior by gears driven by a motor responsive to the output of said second electronic means and guide teeth on the exterior of the timing belt, said guide teeth having the same spacing as the slots of the track and meshing with the slots of the track when the model car is set down on the track, said guide teeth having said metallic brushes at their extremities for the purpose of contacting said common track terminals in the bottom of said slots, said key means being held firmly against the track by spring tension, a metallic return brush depending from said model car and held firmly against the upper surface of the track by spring tension and making electrical contact with the common return terminals, said return brush providing the common return circuit for the electrical signals on the common track terminals, said multiplexed electrical signals comprising pairs of frequency multiplexed signals, said demultiplexing means comprising narrow-band tuned amplifiers in each model car to select a particular pair of frequency multiplexed signals and to separate one frequency of said pair from the other, said demodulating means in each mode car following each of said tuned amplifiers comprising an envelope detector and lowpass filter, said controller comprising means to generate a control voltage consisting of two amplitude modulated subcarrier frequencies and to apply said control voltage to said common track terminals. 

1. In a model car racing system, the combination of at least one model car, a model track having a multiplicity of adjacent parallel paths following the course of the track, said parallel paths consisting of parallel slots in the surface of the track, electrical terminals on the track interspersed among said parallel paths for the purpose of supplying voltages to said model car to control its speed and steering independent of one another and independently from one model car to another regardless of the displacement of said model car along or across the track, said interspersed electrical terminals comprising separate sets of terminals, each model car including means responsive to separate control voltages to independently vary the speed and steering thereof, each model car including means for receiving control voltages from a single set of said terminals, said receiving means including metallic brushes depending from said model car and making electrical contact with the electrical terminals on the track for the purpose of receiving said control voltages, key means depending from each model car and engaging at least one slot of the track for the purpose of guiding each model car around the track on any of said parallel paths and for the purpose of locating each model car in a definite position relative to the interspersed electrical terminals in order that said depending metallic brushes may contact the appropriate electrical terminals, control means for supplying control voltages to each model car independently through said interspersed electrical terminals for the purpose of adjusting the speed and steering of each model car, first electromotive means in said model car responsive to said speed control voltage and supplying a driving torque to the wheels of said model car for propelling said model car along the track at the desired speed, second electromotive means in said model car responsive to said steering control voltage and supplying a force for displacing said key means and the attached model car to an adjacent path of the track in a direction and at a rate determined by the steering control voltage, whereby each model car may be individually controlled by its own driver, and whereby said model car may be steered to any position across the width of the track by the actuation of the steering control voltage at any time the driver so desires, said model car at all other times being guided along the course of the track in the path to which it had last been steered, and whereby said model car may be controlled as to speed independent of the position across the track to which it has been steered.
 2. In the model car racing system defined in claim 1, wherein said terminals include a speed control terminal and a steering control terminal in each slot having the form of continuous metallic strips on the bOttom of and following the entire length of said slots, a common return terminal for the speed and steering control voltages in the form of continuous metallic strips on the surface of the track in between and following the entire length of said slots, said terminals of like function in alternate slots being connected together to form separate sets of terminals, each separate set of terminals supplying control voltages to a different model car, said key means comprising a timing belt rotated from its interior by gears driven by a motor responsive to the steering control voltage and guide teeth on the exterior of the timing belt, said guide teeth having the same spacing as the slots of the track and meshing with the slots of the track when the model car is set down on the track, said guide teeth consisting alternately of electrically active teeth and electrically inactive, or dummy, teeth, said dummy teeth providing more complete meshing of said key with the track, said active teeth including said metallic brushes, said brushes being in the form of first and second metallic pickup brushes at the extremity of each said active tooth for the purpose of contacting the speed and steering control terminals, respectively, in the bottom of a slot, said first pickup brush being connected to and supplying power to the speed control motor in said model car and said second pickup brush being connected to and supplying power to the steering control motor in said model car, said key means being held firmly against the track by spring tension, a metallic return brush depending from said model car and held firmly against the upper surface of the track by spring tension and making electrical contact with the common return terminals, said return brush providing the common return circuit for the speed and steering control voltages applied to the speed and steering control motors, respectively, a speed and steering controller for each model car comprising a power supply and a first and second rheostat, said rheostats controlling the magnitude and polarity of the voltage supplied to the speed and steering control motors, respectively, whereby a model car which is on the track with its key means engaging the slots of the track can receive speed and steering control voltages through only one of the separate sets of track terminals, and whereby when the steering control voltage is supplied to said model car said timing belt turns, moving said key means and the attached model car sidewards across the track under the control of the driver until the steering action is terminated by the driver, and whereby when no steering control voltage is supplied said model car continues to be guided around the track by said key means engaged in the slots of the track to which it had last been steered.
 3. In a model car racing system, the combination of at least one model car, a model track having a multiplicity of adjacent parallel paths following the course of the track, said parallel paths consisting of parallel slots in the surface of the track, electrical terminals on the track along said parallel paths, said electrical terminals being used in common by each model car, said electrical terminals providing a direct-current supply voltage and control voltages to said model cars to control their speed and steering independent of one another and independently from one model car to another regardless of the displacement of said model car along or across the track, said control voltages comprising pairs of multiplexed electrical signals, each model car including first and second electronic means responsive to a particular pair of said multiplexed signals to independently vary the speed and steering thereof, each model car including means for receiving said control voltages from said electrical terminals, said receiving means including metallic brushes depending from said model car and making contact with the electrical terminals on the track, key means depending from each model car and engaging at least one slot of the trAck for the purpose of guiding each model car around the track on any of said parallel paths and for the purpose of locating each model car in a definite position relative to said electrical terminals in order that said depending brushes may contact said electrical terminals, power supply means providing a direct-current supply voltage to said electrical terminals, a controller for each model car to provide said control voltage, the controller for a particular model car being actuated by the driver of said particular model car, said first and second electronic means within each model car being powered by said direct-current supply voltage, said first electronic means responsive to one of said pair of multiplexed signals and said second electronic means responsive to the other of said pair of multiplexed signals, said first and second electronic means each comprising demultiplexing means, demodulating means and amplifying means, first electromotive means in said model car responsive to the output of said first electronic means and supplying a driving torque to the wheels of said model car for propelling said model car along the track at the desired speed, second electromotive means in said model car responsive to the output of said second electronic means and supplying a force for displacing said key means and the attached model car to an adjacent path of the track, whereby each model car may be individually controlled by its own driver, and whereby each model car may be steered to any position across the width of the track at any time the driver so desires, said model car at all other times being guided along the course of the track in the path to which it had been last steered, and whereby said model car may be controlled as to speed independent of the position across the track to which it has been steered.
 4. In the model car racing system defined in claim 3, wherein said electrical terminals include common track terminals comprising a single continuous metallic strip on the bottom of and following the length of each slot, said metallic strips in the various slots being connected together electrically, a common return terminal for the electrical signals supplied on said common track terminals in the form of continuous metallic strips on the surface of the track in between and following the entire length of said slots, said key means comprising a timing belt rotated from its interior by gears driven by a motor responsive to the output of said second electronic means and guide teeth on the exterior of the timing belt, said guide teeth having the same spacing as the slots of the track and meshing with the slots of the track when the model car is set down on the track, said guide teeth having said metallic brushes at their extremities for the purpose of contacting said common track terminals in the bottom of said slots, said key means being held firmly against the track by spring tension, a metallic return brush depending from said model car and held firmly against the upper surface of the track by spring tension and making electrical contact with the common return terminals, said return brush providing the common return circuit for the electrical signals on the common track terminals, said multiplexed electrical signals comprising pairs of frequency multiplexed signals, said demultiplexing means comprising narrow-band tuned amplifiers in each model car to select a particular pair of frequency multiplexed signals and to separate one frequency of said pair from the other, said demodulating means in each model car following each of said tuned amplifiers comprising an envelope detector and low-pass filter, said controller comprising means to generate a control voltage consisting of two amplitude modulated subcarrier frequencies and to apply said control voltage to said common track terminals. 